The Final Solution
by PadfootProngsMoonyJCC
Summary: DO NOT READ IF YOU HAVEN'T SEEN SHERLOCK S4 E3 This is The Final Problem with a twist. Add in another sister, and a girl that is very close to the bakerstreet boys especialy one high-functioning sociopath, and you get a different story all together. Welcome to The Final Solution.
1. Chapter 1

**A/N : This chapter is shorter than most as it is just introducing the characters my best friend and I created. Hope you enjoy. Next chapter will be up today.**

 **BACKSTORY (NATALIA) :** Natalia Shawcross met Sherlock when she was brought over from the states by her British uncle Greg Lestrade to help him with a case that even Sherlock could not solve alone. Natalia was a well known detective in the states being known for her work alongside some of the biggest heroes in the world. She was the unmasked hero.

With her telekinesis and her supreme intelligence she is exactly the person Sherlock needed, and when they met 5 years ago, they formed an unbreakable connection.

Now Sherlock needs her more than ever, with the emergence of a sister he didn't know existed and a brand new, more complicated mystery arising, Natalia and Sherlock will need to rely on each other more than ever. Especially when Evangeline gets involved...

 **BACKSTORY (EVANGELINE) :** As far as the Holmes brothers were concerned, Sherlock's twin sister Evangeline was dead. She was said to have died in the fire that the youngest Holmes started. They never found the body.

Years later, Evangeline finds herself the therapist of one bereaved John Watson, the best friend of her twin brother. Her job as a therapist is made easier by her extension of the well known Holmes ability. Evangeline is telepathic.

In order for Euros to infiltrate the Bakerstreet pair she needed access to John and Sherlock without them noticing so she disguised herself as her older sister, placing her sister in the place that she had been trapped in for years. Sherrinford...


	2. Chapter 2

**A/N : This is the first proper chapter of The Final Solution. Hope you enjoy. :)**

 **Natalia POV**

 _Meet me at MH's. I need your help. ~ SH_

The cryptic text from Sherlock came as I was sat in the flat I shared with said sociopath. One thing I had learnt from the last 5 years was that Sherlock Holmes never asked for help, at least not out loud. What had he got himself into now?

I remembered the first time I met the detective. With his long, sweeping coat and over defined cheekbones, he caught my attention from the second he waltzed onto the crime scene.

 _ **Flashback to 5 years ago**_

"Is he always late?" I asked my uncle, Greg Lestrade, as I tapped my foot impatiently. I wasn't used to waiting for people, that's what happens when you work with the fastest man alive.

"Oh yeah. He refuses to come in a police car so gets a cab. And be prepared for him to call you all manner of things except your name. I've known the bloke for years and he has never called me Greg." He said, I huffed annoyed now. I fly for hours across an ocean for this case and he can't even be bothered to turn up on time when he has to come down the road!

"There he is!" My uncle exclaimed. 'Finally' I breathed, looking up at the famed detective. Okay I've worked with Oliver Queen, and don't get me wrong he is hot but Sherlock… Wow.

Focus Natalia!

"You took your time." I said glaring slightly. Sherlock looked taken aback for a split second before looking at my uncle and back at me.

"What is your niece doing at the biggest case of the last two years Graham. I cannot be distracted by your foreign relatives." He said coldly.

"How? Nevermind I really need to learn to not be surprised anymore." My uncle shook his head.

"Natalia Shawcross. I heard you needed my help. Pleased to meet you Dr Watson." I turned to the man standing slightly behind Sherlock for my last comment.

"Pleasu…"

"I don't need help. I am the world's first consulting detective and the only high-functioning sociopath. I don't need help from silly little girls." Sherlock interrupted.

I ignored him and turned to my uncle. "Now he has decided to show up shall we get to work? Do try to keep up." I finished, aiming the last comment at Sherlock walking into the building.

 _ **End of Flashback**_

That was how I met Sherlock Holmes. Over the last five years we have grown close, we even went to John and Mary's wedding together.

 _ **Flashback to John's wedding**_

"Are you sure we have to go Talia? It's just a piece of paper." Sherlock asked me as I straightened his tie.

"Yes. It's John. Your best friend. We don't have a choice." I responded before getting rid of the tie. "You look better without it." I said, undoing the top 3 buttons of his shirt.

"Come on then. Let's get this over with." Sherlock said striding out of the flat. I shook my head, picked up my purse and followed him.

 _ **End of flashback**_

That was a good day. I think that might have been the day when I realised that my feelings for Sherlock may have changed. I'd gone from strongly disliking him to falling in love with him. And I wish I hadn't. It's Sherlock, he's not as cold and unfeeling as he pretends to be, but I don't think he knows how to love. But part of me hopes he could learn.

I stop reminiscing and stand up from Sherlock's chair, and head to Mycroft's.

Turns out Sherlock just wanted me as back up to scare his brother. I swear sometimes I hate that man. I was comfy. Although at least I found out more about Euros, and I expect we'll find out more tomorrow.

"This is family." Mycroft hissed, wanting me and John to leave clearly. Sherlock pulled me from the arm of his chair to his lap and glared at Mycroft.

"They stay." Leaving no room for negotiation.

"So what was the age gap?" John asked, clearly feeling slightly uncomfortable.

"7 years between myself and Sherlock and Evangeline. 1 year between the twins and Euros." Wait what?

"Twins?" I asked on behalf of everyone but Mycroft.

"Yes. Evangeline died very young. It was Euros who caused it."

"So why did they lock her away." Sherlock said, seeming to have ignored everything Mycroft just said.

"Euros was a strange child. Even from the beginning. She knew things that were impossible to know. Evangeline too. Euros started a fire, at the family ancestral home. We all got out, Euros too, but Evangeline. She died, they never found her body. And then there was Redbeard. She killed him too."

"Redbeard?" John asked.

"My dog." Sherlock said quietly. Seeming to have finally taken in the information about his sisters.

"So they took her away - where?" John asked, being the spokesperson of the group.

"Yes. Somewhere we all thought would be secure. Not secure enough apparently. She started another fire." Mycroft responded almost sadly.

"So where is she now?" I asked the eldest Holmes.

"There's a place called Sherrinford. An island. It's a secure and very secret installation whose sole purpose is to contain what we call the uncontainables. The demons beneath the road? This is where we trap them. Sherrinford is more than a prison, or an asylum. It is a fortress, built to keep the rest of the world safe from what is inside it. Heaven may be a fantasy for the credulous and the afraid. But I can give you a map reference for hell. That's where our sister has been since early childhood. She hasn't left, not for a single day. Whoever you three met, it can't have been her." Mycroft explained. Just as he finished a sound, no a song, started to play from some kind of drone entering the room.

Sherlock stood up quickly bringing me with him as we all backed up.

"What is it?" John asked.

"It's a drone." Mycroft responded.

"Yeah I can see that. What's it carrying? What's that silver thing on top of it, Mycroft?" John quickly said, as well all got closer to the corners of the room.

"It's a DX-707. I've authorised the purchase of quite a number of these. Colloquially, it is known as the patience grenade."

"Patience?" I said nervously.

"The motion sensor has activated. If any of us move, the grenade - will detonate." Mycroft said. I froze, and felt Sherlock tense beside me.

"How powerful?" John asked barely opening his mouth.

"It'll certainly destroy this flat and kill anyone in it. Assuming walls of reasonable strength, your neighbours should be safe, but as it's landed on the floor, I am moved to wonder if the cafe below is open."

"It's not." I said simply.

"Mrs Hudson." I said after a moment's pause.

"She'll be safer in a few minutes. She keeps the vacuum cleaner at the back of the flat." Sherlock stated.

"So we move then." I said trying not to shake. "John. Mycroft, can John phone his daughter, little Rosie. Just in case." I desperately said.

"I'm sorry Dr Watson. Any movement will set off the grenade." Mycroft replied, I tried not to let out the sob that was in my throat.

"What's the response time? Once we're mobile how long before detonation?" Sherlock asked his brother.

"We have a maximum of three seconds to vacate the blast radius."

"John, Talia and I will take the windows. You take the stairs, get Mrs Hudson out too." Sherlock decided.

"Me - you're faster."

"You're closer. Speed differential won't be as critical as distance."

"Agreed." Mycroft said reluctantly.

"She's at the back of the flat." I stated.

"We move in 3. 3," Sherlock started to count down. "2," I shut my eyes. "1." We ran.

Sherlock grabbed my hand launching me over the chair before jumping over himself, before picking me up and jumping out the window, shielding me from the blast.

Without realising I slowly lowered us to the floor, John landing with a thump next to us.

"Oops. Sorry John." I said as he stood up wincing slightly. I still hadn't let go of Sherlock.

"We made it." John said almost laughing in glee. It hit me. We did. We survived the insurvivable. Again. I laughed with him and soon Sherlock joined in. We calmed down and we all turned to Sherlock as the leader. I guess he always has been.

"Where to now?" I asked Sherlock.

"Sherrinford…"


End file.
